Most Ufologists don't talk about alien police forces. One of the reasons could be is that they're too damn scary. Even a gray or reptilian ET would be afraid of the thing above.The powers that it possesses would be unknown to many alien races.

I could just see the officer above pulling over a reptilian/gray spaceship. "It appears you're conducting human abductions without informed consent or compensation. You will come with me or be annihilated. Non-compliance is not tolerated".